- lac "red resinous substance," 1550s (perhaps via M.Fr. lacce), earlier lacca (early 15c., from M.L. form lacca), from Pers. lak, from Hindi lakh (Prakrit lakkha), from Skt. laksha "red dye," which according to Klein is lit. "one hundred thousand," in reference to the insects that gather in great numbers on the trees and make the resin run out. But others say lakh is an alteration of Skt. rakh, from an IE root word for "color, dye" [Watkins]. Still another guess is that Skt. laksha is related to English lax, lox "salmon," and the substance was perhaps originally so called from being somewhat the color of salmon [Barnhart].
Etymology dictionary. 2014.